Head box for a papermaking machine

Claim 2

A head box for a papermaking machine comprising a pair of oppositely disposed sidewalls converging towards each other to form a nozzle duct and a pulp exit throat at one end of said nozzle duct; a distributor between said sidewalls of said nozzle duct, said distributor having a plurality of pulp distributing ducts extending therethrough towards said throat, each said duct having at least one step-like widening therein; and an insert mounted on said distributor between said sidewalls, said insert forming a plurality of terminal sections for said distributing ducts, each said terminal section being disposed in communication with a respective duct downstream of said widening therein relative to a flow of pulp therethrough, said terminal sections being disposed to converge towards said throat.

Claim 3

A head box as set forth in claim 1 wherein each said distributing duct has an intermediate section upstream of a respective terminal section, said intermediate sections of said distributing ducts extending in parallel to each other.

Claim 4

A head box as set forth in claim 2 wherein each said distributing duct has a pair of consecutively arranged sections disposed on opposite sides of said widening with said section downstream of said widening being of a narrowing cross-sectional shape in the pulp flow direction.

Claim 5

A head box as set forth in claim 1 wherein a pair of adjustably mounted lips form said sidewalls, said lips being adjustable in the planes of said sidewalls to vary the size of said throat.

Claim 6

A head box as set forth in claim 1 wherein said terminal sections in a central region of said nozzle duct are longer than said terminal sections in an outer region nearer said sidewalls.

Claim 7

A head box as set forth in claim 1 wherein said distributing ducts converge toward said throat with each said duct extending along a straight centerline.

Claim 8

A head box as set forth in claim 1 wherein said terminal sections converge towards said pulp exit throat while the wall thicknesses of said insert remain constant.

Claim 9

A head box for a papermaking machine comprising a supply pipe for receiving a flow of pulp; a pair of oppositely disposed sidewalls converging towards each other to form a nozzle duct and a pulp exit throat; a distributing block mounted on said supply pipe to distribute a flow of pulp from said pipe into and through said nozzle duct, said distributing block including a distributor having a plurality of pulp distributing ducts extending from said pipe towards said throat, each said duct having at least one step-like widening therein; and an insert mounted on said distributor between said sidewalls, said insert forming a plurality of terminal sections for said distributing ducts, each said terminal section being disposed in communication with a respective duct downstream of said widening relative to a flow of pulp therethrough, said terminal sections being disposed to converge towards said throat.

Claim 10

A head box for a papermaking machine comprising a supply pipe for receiving a flow of pulp; a pair of oppositely disposed sidewalls converging towards each other to form a nozzle duct and a pulp exit throat; a distributing block mounted on said supply pipe to distribute a flow of pulp from said pipe into and through said nozzle duct, said distributing block including a distributor having a plurality of pulp distributing ducts extending from said pipe towards said throat, each said duct having at least one step-like widening therein; and an insert mounted on said distributor between said sidewalls, said insert forming a plurality of terminal sections for said distributing ducts, each said terminal section being disposed in communication with a respective duct downstream of said widening relative to a flow of pulp therethrough, said terminal sections being disposed to converge towards said throat.

Claim 11

A head box as set forth in claim 8 wherein said insert includes a plurality of walls disposed at right angles to each other in intersecting relation.

Claim 12

A head box as set forth in claim 8 wherein said insert includes a plurality of bent walls and interconnecting walls forming terminal duct sections of pentagonal and hexagonal cross-sections.